We will develop genetic approaches in the bacterium Erwinia carotovora to determine the location, organization and regulation of the genes involved in the production of soft-rot disease of plants. Our initial studies will involve the isolation and genetic mapping of nonpathogenic mutants. The mutants will be isolated by transposon-mediated mutagenesis and by chemical mutagenesis. The mutations will be localized on the E. carotovora chromosome by interrupted mating experiments between Hfr donor stains and F - recipient strains. Complementation tests will be performed to determine if the linked mutations are in one or more cistrons. The regulation of genes involved in pathenogenesis will be studied using gene fusion and recombiant DNA techniques.